Electrical measuring instrument.



PATENTED AUG. 25, 190s.

T. W. VARLEY. l ELECTRICAL MEASUEING INSTRUMENT.

APPLICATION FILED DBO. 26. 1902.

I0 MODEL.

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UNITED STAT-Es THOMAS W. VARLEY,

Patented August 25, 190B.

or NEW YORK, N, Y.

ELECTRICAL MEAYSURING INSTRUMENT.

SPECIFIGATIONforming part of Letters Patent No. 737,303, dated August 25, 1903.

Application filed December 26, 1902. Serial No. 136,556. (No model.)

T0 aZZ whom t may concern:

Be it known that I, THOMAS W. VARLEY, a i citizen of the United States, and a resident of New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Electricali Measuring Instruments, of which the following is a specification.

lMy invention relates to an improvement in electrical measuring instruments whereby a true reading of the same may be had unaffected by external magnetic influence.

vThe invention is applicable .to electrical measuring instruments of variouskinds; but for convenience of description and illustration I have shown the same in connection with an alternating-current'voltmeten In the accompanying drawings, Figure 1 is a plan view of an alternating-current voltmeter. Fig. 2 is a central vertical sectional view on the line A B of Fig. 1, and Fig. 3 is a diagrammatic view of the electric circuits as used in my improvement.

Similar letters indicate similar throughout the several views.

The general construction and operation of the instrument illustrated being'similar lto that shown and described in UnitedStates Letters Patent to Weston, Reissued .I une 28, 1892, No. 11,250,and forming no part of my invention, I shall but tersely indicate its parts for the better understanding of my invention. v

The instrument illustrated has a iixedor stationary coil a and a coilv b oscillating orvibrating on inclosed pivots in the fieldv of force of said stationary coil,-said coils being electrically connected. Thelvibrating coil b, on the passage of the current through the circuit, including both coils, assumes an angular position, depending upon the difference of potential between the terminals of the circuit. The reversals of the current in both coils occur simultaneously, and hence an index or pointer c, connected to the movable coil b, is always deflected in the same direction, thus indicating the extent of said angular movement upon a suitable scale d. e is an ordinary resistance-coil supported on the base fin any suitable manner. The normal or Zero position of the vibrating coil b when no current is passing through the inparts strument is ina plane passing through the longitudinal axis of the Iixed coil d, and the pointer c is adjusted so as to mark zero on the scale d when the vibrating coil b is inr this position.

The electrical connections of such an ining through fixed coil a (here shown as con-vy sisting of two parts) by means of wire 11, and through vibrating coil b by means of wire j,

and thence through resistance-coil e to bind-Q Ving-post h. If the instrument is placed inv operation Where there are external magneticl influences acting upon t-he same, ysuch external magnetic iniiuence will cause the instrument to vary from the true reading.

invention. l

v In my improvement l have provided a false base lo, to which the instrument proper is pivoted by means of pivot-pin Z in Vertical alinement with the center of the vibrating coil b.

vClamped to but rotatable on pivot-pin Z is an larm m, bent around the fixed coil o, and carrying at its upper end a normal index n. At

the upper end of the arm fm is a thumb-screw o, projecting through the cover of the instrument, but free therefrom, by means of which the arm is adapted to be rotated on pivot-pin l. I provide an additional binding-post p and connect the same by'means of wire r with wire j.

` The operation of the apparatus is as follows: One terminal is connected with binding-post p and the other with binding-post h. The current will then flow through vibrating coil b only, and if external magnetic influence is present pointer c will indicate the effect of the same on scale d. The instrument is then swung on pivot-pin Z until pointer c indicates zerov on scale d. Normal index n is then turnedy by means of thumb-screw o toV register with pointer c. The terminal connected with binding-post p is then disconnected and connected with binding-post g, the current then flowing along the circuit irst hereinbefore described and detlecting pointer c in the normal way. The instrument is then again swung on pivot-pin l until normal index n It is to overcome this defect that is the object of my Ioo registers with pointer c on scale d, thus indicating the true reading unaiected by external magnetic influence.

It is obvious that the details of construction may be varied or that the improvement may be adapted to other forms of electrical measuring instruments than that illustrated without departing from the spirit of my invention, and I do not restrict myself either to such details or to the adaptation shown.

Having described myinvention and in what manner the same may be performed, what I claim, and desire to secure by Letters Patent of the United-States, is-

l. An electrical measuring instrument, a suitable su pport, a pivotal connection between said instrument and said support whereby the instrument may be swung laterally relative to such support and means for indicating the extent of lateral swing.

2. An electrical measuring instrument, a suitable support, a pivotal connection between said instrument and said support whereby the instrument may be swung laterally relative to such support and means mounted on said support for indicating the extent of lateral swing.

3. An electrical measuring instrument, a suitable support, a pivotal connection between said instrument and said support whereby the instrument may be swung laterally relative to such support, and means independent of the instrument mounted on said support for indicating the extent of lateral swing.

4. In an electrical measuring instrument having a fixed and a movable coil electrically connected, means for independently electrifying the movable coil whereby the latter is free to respond to exterior magnetic influence.

5. In an electrical measuring instrument having a fixed and a movable coil electrically connected, means for independently electrifying the movable coil whereby the latter is free to respond to exterior magnetic iniiuence and means independent of the movable coil for marking its deflection.

6. In an electrical measuring instrument having a fixed and a movable coil electrically connected, means for independently electrifying the movable coil whereby the latter is freelto respond to exterior magnetic influence, a suitable support, a pivotal connection between said instrument and said support and means mounted on said support to mark the position of the movable coil.

7. In an electrical measuring instrument having a xed and a movable coil electrically connected, means for independently electrifying the movable coil whereby the latter is free to respond to exterior magnetic influence, means independent of the movable coil for marking the deflection thereof, and means adapted to permit the instrument to be swung laterally whereby the deflection of the movable coil may be caused to register with said independent means.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

THOMAS W. VARLEY. Witnesses:

GRACE L. HEASLEY, SEABURY C. MAsTIoK. 

